CCG-0941 Interleukin therapy (IL-2)after consolidation chemotherapy for AMLCCG-0941 was a toxicity/feasibility study of Chiron IL-2 after consolidation chemotherapy for AML. Six children received IL-2 at CHOP and to date 25 have received IL-2 nationally. The results of the first 22 children are summarized below. Patients were 0.6 to 16.9 years old (median 6.5 years) and were a median of 6 months from diagnosis. All had received intensively timed 5- or 6-drug induction therapy (dexamethasone, cytarabine, 6-thioguanine, etoposide idarubicin and/or daunorubicin) and post-remission consolidation therapy with high dose cytarabine/L- asparaginase and intrathecal cytarabine. High dose lL-2 (9x106U/m2) was given in the hospital as a continuous infusion (CI) on days 1-4; low dose IL-2 (1x106U/m2) CI was infused at home on days 10-18. All patients received prophylactic antibiotics. Patients experienced the following toxicities: fever grade 1 or 2 (13) hypotension grade 1 or 2 (6), grade 3 (1); grade 3 capillary leak (3); infection (1). There was no renal toxicity. All received 1 or 2 red cell transfusions to maintain a hematocrit >35% and at least 1 platelet transfusion to maintain a count >50x109/L. None required intensive care or pressors. Immunologic studies were as follows: Median Change Pre IL-2 Day 18 P value ALC (n=18) 1213 4008 <0.001 CD3 (n=13) 826 2430 <0.00 CD56 (n=13) 119 654 <0.001 IL-2 r (n=15) 142 747 <0.001 IL-2 caused no life-threatening morbidity in this setting. IL-2 significantly increased the absolute lymphocyte count(ALC), CD3 subsets and IL-2 receptor levels in all patients and CD56 in all but one. CCG-0941 is now closed to patient entry. No new patients will be treated at CHOP.The current CCG randomized trial, CCG-2961, measures impact of IL-2 on outcome.